From the late 80s (when I got into O gauge) through something like 2000, Postwar was hot around here, and many collectors/operators didn't seem that interested in anything else. The prices for Postwar had gone through the roof. At some local TCA meets, it seemed like all the members' attention was on the Postwar items, and not so much the newer stuff. A lot of the newer stuff was selling, but Postwar was the gold standard.
In the last 25+ years, a lot of those who were nuts about Postwar (and grew up with it) are gone, and technology and the move to scale has transformed the O gauge world. Certain Postwar, if it's in excellent condition, still brings high prices, but the rest has tumbled in value. There's far less interest in it, with most buyers these days wanting the latest features - refined sound systems, DC can motors with cruise, constant voltage directional lighting, electrocouplers, scale details and add-on parts, etc.
The nostalgia value of Postwar is still there for many, though, so it still has some allure, but it's not as widespread as it used to be.